Numerous wet scrubbing processes have been developed which are used to remove sulfur dioxide from gaseous streams. Particularly useful are processes which remove sulfur dioxide from hot combustion gas streams, such as gases resulting from the combustion of fossil fuels in power plants. Such removal is believed to alleviate the problem of acid rain which has had a negative effect on the environment and has become the subject of government regulation.
An example of a wet scrubbing system where magnesium components are used to remove sulfur dioxide from a gaseous stream is described in U.S. Pat. No. 5,039,499 to Donald H. Stowe, Jr., where a clear liquor scrubbing solution of magnesium components is used, where scrubber effluent is oxidized to produce gypsum as a by-product. U.S. Pat. No. 5,084,255, to John W. College and Lewis B. Benson, the inventors of the present process, also describes such a process, where a more readily dewatered sludge is formed, and a gypsum by-product recovered.
In such processes, increase in the rate and/or amount of dewatering of the sludge and any provision of a saleable by-product are desired in order to reduce the cost to the user of the desulfurization process.
It is an object of the present invention to provide a process for desulfurization of a sulfur dioxide-containing gas while producing a saleable by-product that can be used in a sulfuric acid/cement production facility.
It is another object of the present invention to produce a more readily dewatered sludge from a magnesium-based wet scrubbing system for removing sulfur dioxide from a gaseous stream.